1. Field of The Invention
The present invention applies to video recorders and, specifically, to video recorders operative with playback at the recording speed and at least one other speed.
2. Description of The Related Art
The problem of creating adequate pictures or images from a video recording played back at the recording speed, and one or more higher speeds in a search mode has been addressed before. It is discussed in a publication entitled xe2x80x9cIntroduction to the 4:2:2 Digital Video Tape Recorderxe2x80x9d by Stephen Gregory of the Sony Broadcasting Company, published by Pentech Press, London, 1988. Chapter 7 teaches a method of pixel-based shuffling for improving the robustness of the system and for recovering pictures in multispeed modes. Briefly, arrays are formed of pixels whose position has been scrambled. The position of the arrays is then scrambled, first within a field and subsequently over four consecutive fields.
This is a very complicated method and yields reasonable results at high speeds, but decreases the picture quality at the lower search speeds. Further, no data compression takes place.
It is an object of the present invention to furnish a method and system in which acceptable picture quality both at higher and lower search speeds is obtained, preferably in combination with data compression.
The present invention is a method of recording data defining a plurality of images on substantially parallel tracks of a recording medium at a recording speed, for playback at said recording speed and at least one additional speed. It comprises the steps of generating a plurality of basic segments for each of said images in response to received image data, each of said basic segments defining an incremental part of an image extending in a first direction and in a second direction transverse to said first direction.
The basic segments are recorded on the tracks as a plurality of sub-sequences each defining a first contiguous part of the image exceeding said incremental part in area. Sequentially recorded sub-sequences in turn define second contiguous parts of the image, greater than the first contiguous parts. All sub-sequences on one track, together defining a third contiguous part of the image exceeding in area said second contiguous part, constitute a sequence. The present invention also constitutes a method for generating display signals for display of an image. Bursts of data (macro-segments) are read from a recording medium at a selected speed exceeding the recording speed of the data. The recording medium has a plurality of tracks each having at least part of one of a plurality of sequential images recorded thereon. Each of the bursts of data comprises data defining a contiguous area of one of the images, while a plurality of bursts, varying in number in correspondence to the ratio of the selected speed to the recording speed, defines all parts of an image.
The data of the read-out bursts is stored in a memory until the plurality of bursts has been received, and then read from the memory in a sequence and at a rate suitable for display, thereby creating the display signals.
The present invention further constitutes a recording medium having a plurality of tracks, a plurality of images being recorded on the tracks, each of said tracks having a data sequence defining a first contiguous area of one of the images, said sequence comprising a plurality of sequentially recorded sub-sequences each defining a second contiguous area smaller than that first contiguous area, each of said sub-sequences comprising a plurality of sequentially recorded basic segments each defining a third area of said image, the plurality of third areas together constituting one of the second areas.
The present invention also constitutes an apparatus for recording video signals defining a plurality of images on a plurality of tracks of a recording medium for replay at the recording speed and at least one higher speed. Coding means are provided for encoding said video signals into basic segments, each basic segment defining an incremental area of one of said images.
Memory means store a plurality of said basic segments, addressing means reading out a plurality of sub-sequences, each comprising basic segments defining contiguous parts of said image, from said memory means in a predetermined order, thereby furnishing read-out sequences. Recording means record the read-out sub-sequences on tracks of the recording medium.
During playback at a speed exceeding the recording speed, only part of the data on each track will be read out. Of this, only a part will have a SNR sufficiently high for use in an error correcting code. This latter part is called a macro-segment herein.
The present invention also constitutes an apparatus for furnishing display signals in response to macro-segments of data read from a recording medium at a speed different from the recording speed. It comprises means for storing the macro-segments together constituting an image, and means for reading out the stored data in a sequence and at a rate suitable for application to display means.